You have a binomial distribution with large number of trials n = 500 
and individual probability of success p = 0.08.


You want to approximate it by the normal distribution.
You should use the mean value m = p*n = 0.08*500 = 40 and standard deviation 

    SD =  =  = 6.0663.


Also, you should use the continuity correction factor.


About approximation of the binomial distribution by normal distribution and continuity correction factor 
see your textbook and/or these Internet sources

https://www.statisticshowto.com/probability-and-statistics/binomial-theorem/normal-approximation-to-the-binomial/

https://online.stat.psu.edu/stat414/lesson/28/28.1

https://stats.libretexts.org/Courses/Las_Positas_College/Math_40%3A_Statistics_and_Probability/06%3A_Continuous_Random_Variables_and_the_Normal_Distribution/6.04%3A_Normal_Approximation_to_the_Binomial_Distribution


    For calculations, you may use your calculator (function normcdf), or Excel spreadsheet (function NORMDIST);
    or online calculator https://onlinestatbook.com/2/calculators/normal_dist.html



(a)  In this case, you should find the area under the normal curve on the left from 49.5
                                                             (using the correction factor)

     P(x < 50) = normcdf(-9999, 49.5, 40, 6.0663) = 0.941  (rounded).



(b)  In this case, you should find the area under the normal curve on the right from 50.5
                                                             (using the correction factor)

     P(x > 50) = normcdf(50.5, 9999, 40, 6.0663) = 0.0417  (rounded).   



(c)  In this case, you should calculate the area under the normal curve between 39.5 and 50.5
                                                                  (using the correction factor)

     P(40 <= x <= 50) = normcdf(39.5, 50.5, 40, 6.0663) = 0.491  (rounded).